The present invention relates to a process for controlling access to a telecommunications network by means of a terminal operating together with a user module. It finds an application in any communication system requiring authentication of the terminals.
Procedures are known, for example from EP-A-0 552 392, which make it possible mutually to authenticate a user module and a terminal. These procedures enable the user to be assured of the authenticity of the terminal to which he presents his module. On the other hand, they do not advise the network regarding the authenticity of the terminal or of the module.
The communication network needs to ascertain and verify the identity of the users in order to ensure proper routing of the communications and to allow billing. Most often, as for example in the case of the European cellular radio telephone (GSM), each terminal is associated with a single user, and authentication of the terminals and of the users is merged.
Currently, the concept of personal mobility is developing, and there is a desire to enable the terminals to be shared by several users. This entails separation between the management of the users and that of the terminals.
Under the layout currently applied to the current GSM network, authentication pertains solely to the user modules. The terminal contains no specific security data. Withdrawal of the user module entails the absence of the authentication data related to the terminal. The latter then becomes dormant and is no longer contactable. When it is moved, especially during a location update procedure, it is the user module (SIM) which is authenticated (see the article "Une application de la carte a microprocesseur: le module d'identite d'abonne du radiotelephone numerique europeen" (An application of the microprocessor card: the subscriber identity module of the European digital radio telephone) by P. Jolie et al., published in l'Echo des Recherches No. 139, 1st quarter 1990, pages 13 to 20). Moreover, if the terminal is envisaged as being shareable by several users for receiving communications, it becomes possible for several users to be logged onto the same terminal during a location update. It can happen that the terminal does not physically possess a user module during a location update; in this case, authentication is impossible and the location update fails, seeing that it must be impossible for the terminals to use radio resources without being associated with users.
In view of the foregoing, a main object of the present invention is to provide a flexible procedure for the combined authentication of a user module and of a terminal.